Steam-turbine.



Patented June 13, 1916.

9. XN` .T

G. F. DE WEIN.

STEAM TURBINE.

APPLICATION min Aus,\5. 19:4.

) wvawXo-u UNITED STATES PATENT OFFICE.

GEORGE F. DE WEIN, OF MILWAUKEE, WISCONSIN, `ASSIGrNOIt TO ALLISCHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATIONOF DELAWARE.

y STEAM-TURBINE.

Specication of Letters Patent.

Original application led February 9, 1914, 'Serial No. 818,153. Divided and this application filed August 15, 1914. Serial No. 856,985.

To all whom t may concern.' A

Be it known that I, GEORGE F. DE WEIN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and Sta-te of Wisconsin, have invented a certain new and useful Improvement in Steam- Turbines, of which the following is a specication.

This invention relates to steam turbines and more particularly to'means for securing the shroud to the blade ends and for properly positioning the blades at one end.

An object of the invention is to provide an assembled blade structure for steam turbines which is simple in construction, eiiclient in operation, and which 'possesses the requisite amount of rigidity and strength, especially to withstand vibration.

y One of the more specific objects is-to provide eflicient means for securing a light shroud to the single-surfaced ends of a plurality of blades, this shroud being provided with means for properly positioning the blade ends both as to spacing and angling the same.

Another object is to provide an imperforate shroud with means for positioning the blades at their ends, the blades and shroud being united by fusion of metal.

This application is a division of application Serial No. 818,153, filed February 9, 1914. i

The expression single-surfaced end as used herein is intended to apply to a blade end which is free from any projection or recess abruptly interrupting the continuity of the end surface of the blade. The expression therefore includes blade ends having surfaces which are either plane or curved, these surfaces being either perpendicular or oblique to the edges of the blades.

Heretofore it has been proposed to fasten ay shroud to blade ends by means of tenons formed on the blade ends and passing through holes in the shroud, the tenons being riveted over the shroud stock. It has also been proposed to fasten a shroud to the ends of the `blade by fusion of metal, for instance by brazing, the blade ends in this case being properly positioned by forming a tenen on each of the blades and inserting the same in correspondingly shaped holes formed in the shroud. The objections to these constructions are, first, that considerable blade stock is wasted in forming the tenons; and, second, that the shroud is weakened at least temporarily, by forming the holes therein for the tenons'. With the use of the present invention these objections are eliminated and a very strong and light shroud structure is produced.

A clear conception of several embodiments of the invention may be had by referring to the drawings accompanying and forming a part of this specification in which like reference characters designate the same or similar parts in the various views.

Figure 1 is an elevation, partly Iin section and partly broken away, of a fragment of one form of blade segment, the section being taken along the line I-I of Fig. 2 looking in the direction of the arrow. Fig. 2 is a plan view of a fragment of the blade Segment shown in Fig. l, a portion of the shroud being broken away. Fig. 3 is a transverse vertical section through the blade segment and shroud shown in Fig. 1, the section being taken along the line III-III of Fig. 1 looking in the direction of the arrow. A Fig. 4 is an elevation, partly in section and partly broken away, of a. fragment of another form of blade segment, the section being taken along the line IV-IV of Fig. 5 looking in the direction of the arrow. Fig. 5 is a plan View of a fragment of the blade segment shown in Fig. 4, a portion of the shroud beingbroken away. Fig. G is a transverse vertical section through the blade segment and shroud shown ,in Fig. 4:, the section being taken along the line VI-VI of Fig. 4 looking in the direction of the arrow. Fig. 7 is a transverse vertical section through still another form of shroud attached to a fragment of a blade. Fig. S is a fragmentary plan view of the shroud and blades such as are disclosed in Fig. 7.

The figures of the drawing disclose rotor or movable blading of a turbine of the parallel low Parsons type, but it is to be understood that the invention is equally applicable to stator or stationary blading as well as to other types of turbines. As disclosed in the drawing, the blades 1 have their inner ends united with foundation segments 3 by fusion of metal, this union of the metals being accomplished by casting the foundation segment 3 directly upon the blade roots. The foundation segments 8 are properly machined for insertion within grooves of the, turbine rotor, the segments being secured in place b v calking or other suitable means. This portion of the disclosure is, however. merely illustrative of one forni of uniting the blades to the; spindle, other well known means being equally feasible. In each of the forms of the invention illustrated, the blades 1 have single-surfaced ends, the end surfaces being disclosed as planes perpendicular to the' working faces of the blades, that is, perpendicular to the blade stock. This formation of the blades with single-surfaced ends permits complete utilization of the blade stock without waste of material such as results when blades are provided with tenons or similar irregularities. As disclosed, the shroud is constructed in the form of a channel having parallel outwardly extending side walls, this construction permitting ready machining of the shroud to bring the same in close proximity to the turbine casing. This invention is not, however, limited to channel Shaped shrouds.

Referring specifically to Figs. 1, 2 and 3,

v the channel shaped shroud 2 is provided with a series of pockets or recesses for the ends of the blades 1. The recesses are yformed by forcing the portions 4t of the shroud stock in line with the blades 1 outwardly out of the normal cylindrical formation of the base of the shroud 2.l The die used in distorting the metal during the operation of forn'iing the recesses, is of the same cross section as a blade, while the backing dieis of any suitable shape adapted to prevent distortion of the portion 6 of the shroud between the blades 1. As the blades 1 when in normal position, are of a projected width greater than the distance between the adjacent surfaces of the side Walls of the shroud 2, the blade edges project into these walls'and the metal directly in line with these edges which is displaced during the distorting operation. will of necess' y have to be forced out of the side walls preferably into previously provided spaces in the backing die. It will be noted that the shroud thus produced is imperforate and has formed directly thereon means4 for properly positioning, that is spacing and angling, the blade ends. After the shroud 2 has been provided with the pockets or recesses, the shroud is brought in contact with the blade ends, the blade ends being inserted within the successive recesses and being thus properly positioned. iVith the blade ends thus properly positioned, the blades and shroud are united by soldering, brazing, welding or other method of producing fusion of metal. In the drawing the brazing process is indicated as having been used, the added fusible material being represented as forming a fillet 5 adjacent the blade ends.

Referring specifically to the disclosure in Figs. 4, 5 and 6, the shroud 12 is provided with a series of recesses for positioning the ends of the blades, said recesses having their bottoms flush with the normal base 16 of the shroud. The recesses in this case are formed by forcing the portions 14 of the vshroud stock between successive blades inserved that in the. form of the invention shown in Fig. 6, it 1s unnecessary to disturb the metal in line with the side walls of the shroud 12 as in the form of the invention shown in Fig. 3. In the dra-wing the means for` uniting the shroud 12 and blade 1 is represented b v the fillet 15 of added fusiblev material, see Fig. 4.

Referring specifically to Figs. 7 and S, the shroud 22 1s provided with local projections 24 on the blade side of the shroud, forming positioning means for the blade ends. The recesses between successive projections 24 are created by the forming of the projections 24. The projections are formed by locally forcing metal from the normal base 26 ofthe shroud stock, between and adjacent successive blades, by means of a movable die having local projections positioned for properly spacing and angling the blades 1. This form of shroud 22 is more especially applicable to the larger sizes of blading because of the increased distance between the limits of transverse contact between the positioning surfaces and one. of the faces of the blade. lVith this form of shroud the recessed projection at a blade is discontinuous with the corresponding recessed projection at an adjacent blade so that there will be less tendency to produce eddying of the steam between the blades. The projections furthermore are located closely adjacent to and conform with the contour of the blade ends thereby tending to permit utilization of the entire working faceof the blade.

In each of the forms of shroud disclosed, it will be noted that the shroud is imperforate (the possible shearing in the form shown in Figs. 7 and 8 not being considered as perforating), being at the same time provided with means for properly spacing and angling the blade ends. These features are of importance; the former since it permits production of a very light shroud of great strength, and the latter because the proper spacingr and angling of the. blades is of great limportance in attaining the highest eliciency in the turbine. The formation of the blades with single-surfaced ends permits utilization of the entire blade stock without waste. The distortion of an impert'orate shroud produces a locally arched structure which when united with the blades by fusion of metal forms a completed structure of great rigidity and strength, especially to withstand vibration. It will also be noted that in each case the shroud is provided with recesses adjacent the blade ends, and with positioning surfaces which coact directly with the working faces of the blades. In some -ases there are projections on the shroud for positioning` the blades. In order to secure proper positioning of the blades, the positioning surfaces should be so formed as to coact with the working faces of the blades both transversely and longitudinally thereof to a consideral'ile extent. This result is more especially easily accomplished in the constructimi shown in Figs. l and 7, although by using excessive pressures on the dies the same result will be attained in the remaining form shown.

It should be understood that it is not desired to be limited to the exact details of construction shown and described except as required by the scope of the appended claims, for obvious modifications will occur to a person skilled in the art.

It is claimed and desired to secure by Letters Patent,`

1. In combination, a blade having a singlesurfaced end, and a shroud of substantially uniform thickness having means for positioning said blade, said shroud being secured to said blade.

i2. In combination, a blade having a singlesurtaced end, and a shroud of substantially uniform thickness having means for positioning said blade, said shroud being secured .to said blade by fusion of metal.

In combination, a blade, and an impertorate shroud of substantially uniform thickness having means for positioning said blade against transverse displacement in all dlrections, said shroud being secured to said blade.

4. In combination, a blade, and an imperforateshroud of substantiall y uniform thickness having means for positioning said blade against transverse displacement in all directions, said blade and said shroud being united by fusion of metal.

In combination, a blade having a singlesurfaced end, and a distorted sheet-metal shroud having surfaces for positioning said blade, said shroud being secured to said blade by fusion of metal.

G. In combination, a blade, and an imperforate distorted sheet metal shroud having surfaces for positioningr said blade, said blade and said shroud being united by fusion of metal.

7. In combination, a blade having a singlesurfaced end, and a shroud having its body portion distorted to form a recess for positioning said blade. said shroud being secured to said blade by fusion of metal.

S. In combination, a blade, and an impert'orate shroud having its body portion distorted to form a recess for positioning said blade against transverse displacement in all directions, said blade and said shroud being united by fusion of metal.

9. In combination, a blade having a singlesurfaced end, and a shroud having projections on the blade side thereof for positioning said blade, said shroud being secured to said blade by fusion of metal and said shroud being of substantially uniform thickness throughout.

10. In combination, a blade having a single-surfaced end, and an impertorate shroud having projections on the blade side thereof for positioning said blade, said shroud being secured to said blade by fusion of metal and said shroud being of substantially uniform thickness throughout.

11. In combination, a plurality of blades, and a locally arched shroud united to said blades by fusion of metal.

In testimony whereof, the signature of the inventor is aflixed hereto in the presence of two witnesses.

G. F. DE WEIN. Witnesses:

HENRY RUDE, IV. II. LIEBER. 

